I would like to take a bit of a different approach than some of the posts before. I really hope this post proves useful for others.
First off, I'm a 24 year old male who has been watching Japanese dramas since I was around 18. I've seen a good share of j-dramas and I find myself liking these genres the most:
drama, romance, and comedy. I am also a big fan of
acting, production, writing, soundtracks, and overall quality (aka looking nice and not cheap).
Here are my top 5 with reasons why:
1. Orange Days -Seeing this drama towards the tail end of my high school life helped me connect with the plot as the main characters were in post secondary. The acting is in my opinion the best I've seen in a j-drama to date. The pair of Shibasaki Kou and Tsumabuki Satoshi are terrific in both acting and in chemistry (which even carried into their personal lives). The plot is a bit hard to relate to, but I felt that everyone was very different and it was enough to keep you interested. Admittedly, the first episode is slow, but at the end you should get sucked in. I've seen the series three times, and I know I will see it again soon.
2. Hana Yori Dango Season 1 - In a totally different turn from my favourite, this romance/comedy comes in next. I'm sure this is one of the top recommendations for people, I don't think I need to add too much. This j-drama is tremendous fun for any teen or young adult. The casting is perfect. There are lots of laughs, dramatic moments, and cute moments. This is one which you can watch multiple times and have fun with.
3. Nodame Cantabile - if you liked Hana Yori Dango, I think Nodame Cantabile will also fit your liking. Ueno Juri is adorable as the odd but lovable character Nodame. Also, Tamaki Hiroshi does a great job as the mean and stern Chiaki. Two people who don't seem to fit together really work and fit, and in the most funny situations. I pretty much had fun watching this from start to finish. I also ended up having a bit more appreciation for classical music by the end
4. Kaseifu no Mita - I wanted to add in a more recent drama to my list just for diversity, and because this series was really great. Kaseifu no Mita is a heavy load of drama to take. We have the maid, Mita, who is as stoic and static of a character that I've ever seen. Then we have a seemingly nice family consisting of a father, two sons, and two daughters. But as we go through we have tremendous character growth from everyone which can make your heart feel nice. This kind of drama I think can really be for a wide range of ages as the children are quite young and relatable, and the adults also have some great plot devices. And hey, there has to be some justification for the 40% rating on the last episode. The acting is great from everyone, the casting was done well, the quality was high, the only reason it is fourth on my list is the plot of the drama near the end was not as good as before. But I was still very satisfied overall.
5. Tatta Hitotsu no Koi -from the writer of Orange Days, I knew I had to check this drama out. We have actors and actresses in their early 20s, who are from different backgrounds and hardships. As a guy I could relate to the main character, Hiroto, who goes about his mundane daily life until he meets a cute and innocent girl, Nao. Not too drama overfilled, the plot is mainly about the relationships and barriers between men and women. This drama is much more on the romantic side, with nothing heavy that you would find in some other dramas (say One Litre of Tears for example).
5 dramas are hard to list, I have a bunch I like!
If anybody has any questions or wants recommendations, feel free to message me. I know there is a great recommendations thread, but if you like the same dramas as I do, I would love to talk about them.